


The Flame of Desire

by NihilismPastry



Series: Requests from Tumblr [16]
Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell, Chubby Reader, Dirty Talk, F/M, Female Reader, Forced Nudity, Kidnapping, Multiple Orgasms, Soul Mate AU, Spanking, gagging, non-con
Language: English
Status: Completed
Published: 2016-11-13
Updated: 2016-11-13
Packaged: 2018-08-30 08:01:51
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,145
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8525188
Author URL: https://archiveofourown.org/users/NihilismPastry/pseuds/NihilismPastry
Summary: Grillby will keep his soul mate, no matter the costs.





	

**Author's Note:**

> A friend had a request come in, but didn't feel they could fulfill it. So, I decided to take it up for them to keep the momentum going! So here's a request for someone! 
> 
> Request: Chubby female reader, handcuffs, multiple orgasms, kidnapping, yandere Grillby, and breeding kink. Please have Reader already be with someone before Grillby.

Grillby was a patient man. He allowed many things to go in his life, that would put other men through hell and back. Some claimed it was thanks to his stubborn personality, others said it was due to his age. The truth was far more simplistic: He just didn't care. After surviving a war, the hell that was the Underground, and asshole humans, other things seemed far simplistic and less important now. Especially when he had his soul mate to worry over. A weak female human that came to his bar every Friday with a tall male human. She was courteous, if not a bit shy and had a love for tequila. 

The moment he felt her soul brush against his own, he had decided that she had to be his. He had tried charming her for months, and bringing her closer to him, but the male human was equally possessive. Most other humans stayed away from his mate when her bastard was around, and more than once the role of protector was outright stripped from him. Logically he shouldn't be jealous of the male, after all he knew his mate longer and held her trust, but his instincts didn't care. They needed his little mate close to him, to properly bond and became of one soul and all that other sentimental bullshit. 

He leaned against the wall of an old apartment building, a cigarette between his fangs. Soot clung to his shirt, and he could still smell burnt flesh. He was hoping a walk would get the smell out, but it wasn't helping. He sighed and pressed his middle finger to the tip of his cigarette. It spurt to life before a purple tinged smoke escaped the tip. The nicotine could do nothing for him, and the magic laced in it was so mild it didn't matter, but it stopped him from just setting the apartment across the street ablaze.

He stared at the double doors at the bottom of the brick building, a small figure sauntering out. She was wrapped in a winter coat, and had a phone in hand. He fished into his pants pocket, and pulled out a cellphone. A pale blue speech bubble flashed on his screen. 'I'm on my way.' 

He typed out a response before trailing his soul mate. He stayed in the shadows, and kept his flames dim enough so she wouldn't notice. No one stopped to question him, or touch his human. In fact, she was rather unassuming compared to some of the rabble milling outside the bars and clubs. When she went up to the specified bar, he slipped in after her, tipping the bouncer when he tried to stop him from entering. The burly male slipped the money into his jacket pocket and let him in.

This particular club was wild and loud. There was bright lights, scantily clad girls, and cheap alcohol. It was the kind of place that you went to in order to cause trouble, or do something marginally illegal. His mate went straight to the bar, and sat on one of the plastic bar stools, her hands on her knees, and biting her bottom lip. She kept her gaze on the crowd, wriggling in the chair every so often. Grillby watched her from the other side of the bar, smoking his second cigarette in the last twenty minutes. If he was human, he would probably be concerned for his lungs.

This part of the mission took patience. If he went to her too soon, she would become suspicious. If he took too long, then she wouldn't want anything to do with him. So for the next twenty minutes, he watched the human wriggle in her seat, turning down the bartender ever time she came around. After the sixth time his mate checked her phone, he got off the wall and began to make his way towards her. Humans skirted out of the way, more than one whispering or glaring as he passed by. For once he ignored, doing his best to keep his calm as he finally approached his human. "Good evening, didn't expect to see you here, Miss."

She looked up from her phone, and a small smile broke out on her face. "Hey, Grillby. My boyfriend wanted to go out on a date, but it looks like he won't be making it. Work." She shrugged and pressed her thighs. "How're you doing? Scoping out the competition again?"

He nodded. "I was recently told this place has a human drink that's very popular right now."

"Cool." She hopped off the barstool, nd smoothed out her skirt. "Well, I'm going to go back home. I only stayed so long because of a song anyway. Have fun, Grillby."

"Do you need an escort?"

She bit her lip, her gaze darting to the door. After a moment she nodded. "If you don't mind?"

He pressed a hand to her lower back, and guided her out of the club. The bouncer that let him in raised an eyebrow, but didn't question it as he led his human down the street. A cold wind blew through the area, bringing with it the stench of burning rubber, and car exhaust. His mate hissed and huddled closer to him on instinct. As such, he brought up the heat of his flames. Not hot enough to burn, but a mellow heat that could be likened to a warm blanket. The woman yawned and leaned further into him, her eyes heavy. "You're pretty convenient."

She sagged against him completely, putting all of her weight on him. If he hadn't been ready for it, she would have fallen onto the gum covered sidewalk. He hoisted her up bridal style, and pressed his lips to her forehead. "Not, convenience, dearest. Fate."

* * *

You felt warm. As if you had been dipped into a sauna, and wrapped in the comfiest towel in existence. You let out a low sigh, and curled further into the warmth, just to hear a low chuckle. You gasped and opened your eyes, just to state up at a ceiling. It was smooth and the cleanest shade of white you'd ever seen. "H-hey-"

Your words died and became a whimper when the vibrator in your pussy was shut off. John had told you to put it in earlier when he had asked you to meet up at the club on Seventh Street. You'd gone home when he told you work had called at the last minute, but then...You just remember being warm.

You sighed and lifted your arm, just to find it not working. You glanced up, and found your arms attached to a metal headboard with handcuffs. You weren't sure why you didn't notice them before, perhaps it was because the metal was so warm? You twisted onto your knees, your skirt riding up higher, and inspected the lock. It looked standard enough, something easy to pick out of. Now if only you had some hairpins...

Your trail of thought died when you felt a warm hand on your exposed ass. "That's rather brazen of you, dearest. Already on your knees for me."

 You twisted around, your eyes widening when you caught sight of Grillby. He hand his hands in his pockets, and his shirt was open, revealing a body entirely composed of violet flames. It wasn't muscular or anything, just a human shape that got the point across. "Did you..."

He knelt down on the bed, the mattress squeaking as he came closer to you. His warm hand trailed up your ass, and under the waist band of your skirt, rubbing your hip. "I'm merely taking back what's mine. I told you we were soul mates from the beginning, but you denied me, so I'm going to prove it to you."

"What?" You jerked your hips back, nearly falling onto the headboard. "You're not my soul mate. If anyone is, it's John-"

"Him?" He took out a plastic bag from his pocket. Inside was a black powder that looked almost like ashes. "You humans have the weirdest case of coupling and denial I've ever seen. Monsters face their reality while you all run away." He opened up the bag, and spread the ashes over the burgundy sheets. "I'll make you see it. One way or another."

He tossed the now empty bag to the side, and grabbed the waist band of your skirt. You kicked out your legs, but squealed when they met burning flames. Without any effort he pulled off your dress, leaving your lower body exposed. You curled your upper body lower to hide yourself, but he grabbed your turtle neck, and ripped it off your body. Your bra clad breasts were now free, and the reality of the situation was starting to hit home. Low whimpers escaped your lips as a warm hand made its way up your hips, across your stomach, and to your bra. He made quick work of it, letting your breasts finally hang free. 

You stared up at him, mouth open, but nothing coming out. He looked so damned pleased, and that scared you more than anything. "L-look, I know you're jealous, but you don't need to do this. We could talk about it over a couple of beers."

He squeezed your chest, the gentle heat helping to make it feel better than it should have. His long fingers dug into the flesh, and you felt his temperature rise. "You're right, I am jealous, but it's nothing that can be talked out." He leaned down and pressed a kiss to your lips, making you shudder when you tasted soot. "We're too far past that."

The flame elemental straddled your hips, making you back into the mattress. He was much bigger than you, and it was nothing for him to use his hips to keep you pinned. Your blood ran cold when you felt the obvious bulge between you and the black fabric. Was he seriously getting off on this situation? The thought made your fear double.  "P-please-!"

He slammed his mouth to yours again, and trailed his hands up and down your sides. It was motion meant to be soothing, perhaps even erotic, and that made you confused. He was trying to rape you. The action was always about self satisfaction, not about the other party. Grillby's lips parted from your own, and his fingers trailed down to your hips. Your heart beat rose when two fingers came closer to your cunt. You shook your head, mouth blubbering out please until you felt two warm fingers in your cunt. You heard the hiss of steam, and something akin to a purr from the fire elemental. You gasped when the vibrator was ripped out of you,then thrown across the room, narrowly missing a mirror. 

It was immediately replaced with his fingers. They were thick and warm, and better than the cheap, plastic dildo you'd had in your cunt. Due to having that inside you for the lady hour or so, you were soaking wet and stretched enough that you took his fingers without too much trouble. Even when you squeezed your cunt, he easily slid past you defenses and began to pump his wrist. His other hand trailed back up to your breast, and squeezed the nipple. It was too hard, and it hurt too much, even his slow thrusts had gotten harder and faster. 

He stared down at you with a smile, looking almost amused at your predicament. His hand moved to your other breast and began the process all over again, leaving behind bruises and swollen flesh. He was being much too rough, and his temperature was rising. Your lower half becoming clouded in steam. "Cum for me, slut. Accept your reward."

You shook your head, but you felt your walls flutter against your will. "No! I-"

A heat deeper than the flames that comprised the bartender, and more powerful than his thrusts rocked your body. You heard the man laugh, but it was like a whisper compared to the thundering in your ears. 

You had cum. 

You had orgasmed from thanks to the monster. The thought made you sick, and your face warm with shame. The man was raping you, yet your body had enjoyed it. Grillby pulled his fingers out of your pussy, and brought them up to his mouth. You jerked your head to the side, staring at the lamp instead of the monster. A deep chuckle reverberated through the room, and you felt lips press against your stomach. "My little mate is so shy. I wonder what your human has to say about it? They say the dust of a monster is still aware of the emotions of the person they're closest too."

"Leave John out of this!"

"To be fair he's hanging around our bed." A purple hand came into view, showing off gritty black soot. Your eyes widened and your mouth went dry as the pieces Dell into place. "Fucking in the dust of your enemies is a long standing tradition. Granted, I had far more work turning your human into dust, but I managed."

Your eyes stung, and you slowly turned to look at the monster. His grin was larger now, showing off teeth that looked sharp enough to bite through bone. He brought his hand to your face, smudging the ashes on your cheek. "You're sick."

He shrugged as he unzipped his pants, revealing a long cock. It was shaped like a human one, but wasn't too thick. What you were more worried about was the face that if he came inside you, would you wind up pregnant. The elemental hauled your hips up, and lined your pussy up with his dick.

"I've been waiting to do this since I met you. That night when you came in, I wanted to bend you over the bar, fuck your brains out, and cum so deep inside you that I could breed you." He pressed his dick into your entrance, and you flinched as it began to stretch you. "And you know what? I still want that. I'm going to fuck you all night, and by the end? We'll have spawn. A bit early for you, perhaps. But a whole millennia waiting for this is more than enough time for me."

You hissed as he shoved himself deeper inside you, hilting into your tight cunt. He lowered himself down, and pressed a kiss to your lips. You tried to bring your jaws down on his tongue, but squealed and tried to back away as his hands heated up. The pain wasn't intense, just light enough to catch your attention, but hard enough so it would still need burn cream. Grillby learned down at you as he began to thrust,the movement sharp and jarring. He had a fast and rough rhythm that made you feel more than you should. Every glide against your walls was pronounced, and you were sure he was hitting your sweet spot ever time. Every time he pulled out, the steam would curl around the both of you, almost making an intimate atmosphere.

The fire elemental hissed and dragged his fingers to your thighs, spreading you further. He pulled out of your pussy, and stared down, the white flames of his eyes holding a predatory look. "I got ahead of myself. I was so eager to feel you, I haven't looked at your properly." He knelt down, embarrassingly close to your pussy. You could even feel his hot breath on your pussy. "So beautiful, precious. Even after all the abuse it's had, you're still lovely."

You were sure he was referring to your boyfriend fucking you, not the actual abuse happening to you. However, one thing that your stupid brain became hooked on was the word beautiful. Not many people called you that, even John had only ever called you cute. Something expected of course, you didn't have the appropriate body top to be called sexy or gorgeous. 

You shook the thoughts away, not allowing your affection starved brain dictate things. This man killed your boyfriend, was fucking him you against your will and in your boyfriend's ashes. The only crime that this demon could commit at this point was killing you, and dumping you in a preschool.

You gasped as you were rolled onto your stomach. He pressed his hand to your back, and hoisted the other around your waist, pulling your ass into the air. You feel something gritty under you, and you did your best not to think about it. 

"Beg me to fuck you."

You whipped your head around to look at him, eyes wide and fingers curled. "No. There's no way you could think-" A resounding slap filled the room, and your ass exploded in pain. You hissed and pressed your forehead back into the bed. "N-no."

Another shock of pain, this time on a different part of your ass. "I can do this all day, precious. Don't try to outlast my patience, I promise you'll loose." He punctuated it with another smack to your ass. "Come on, slut. You know you want it." He smacked your ass again, this time increasing the temperature in your hand. Your whimpers turned into screams. "It would stop if you begged, precious."

"Please," The words left your lips, taking part of your soul with it. "I want you to..."

"To what, dearest?" His hand gently caressed your ass, his temperature turned down enough to be damn near soothing.

"..."

"Dearest?"

"Fuck me."

He gave a low laugh as he leaned down, pressing his lips to your cheeks. "As you wish."

He slammed his cock right into you without delay, and began to thrust at a hurried pace. His grunts and moans mingled with your muffled whimpers as he pounded into you. He kept up a steady pace, one hand wrapped around you waist, the other still on your back. The one on your waist lowered, and a finger dove in to find your clit. You hissed and fought the moan that wanted to break loose. Why were you so close to cumming? He hadn't done anything you liked, yet you were right on the precipitous of another orgasm.

It came in a flurry of sparks and garbled 'sorrys', your eyes shut as you embraced the pleasure. You could still feel the monster behind you, his pace becoming sloppy and his grip harder on you. But now you felt hollow, closer to a doll than human. You couldn't even bring yourself to react as you felt something thin and warm bust inside of you. Not even when the monster pulled out, and laid down next to you, bringing you close to his body. 

He turned you over, cradling a hand to your cheek, eyes tender as they stared down at you. "And now you're rightfully mine."

**Author's Note:**

> Not sure if this is what the requester will be expecting, but I hope it's close? I'm kinda on edge about it because it's a little more extreme than my last non-con story...
> 
> Know what isn't on edge? My tumblr! http://nihilismpastry.tumblr.com
> 
> Also, check out Life_Sans_Sin's tumbly. They're the one who handed over the request! http://life-sans-sin.tumblr.com


End file.
